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Newly developed gene test may help identify early-stage Candidemia

Researchers at Duke University's Institute for Genome Sciences & Policy have reportedly developed a new gene-expression test capable of identifying early signs of the life-threatening infection known as Candidemia.

Commonly found in very sick or immunocompromised patients, candidemia is caused by the fungal pathogen Candida. If not identified immediately, the blood stream infection can kill between 10 and 15 percent of patients within the first 24 hours. If the disease goes undetected for 72 hours, the mortality rate rises to 30 percent.

People at a high risk of developing the infection include HIV/AIDS patients, people with extreme neutropenia, babies with low birth weight and those with intravenous catheters. Symptoms of candidemia range from mild to extreme, and are often compared to feeling of having the flu.

Over the years, the greatest challenge for doctors in diagnosing candidemia is that its symptoms are commonly associated with other serious bloodstream infections. It often takes hospitals as long as three days to receive the results of blood culture tests, which are not always completely accurate.

Due to the fast-acting nature of candidemia, developing an early detection method is paramount. Using a mouse model, the scientists from Duke believe that they have identified a group of genes that can help doctors distinguish patients infected with candidemia from those afflicted with different types of blood infections.

In the study, the researchers infected one group of lab mice with candidemia and another with a similar staph infection. They then compared their blood samples to those of healthy subjects.

When looking at the genes associated with immune response, the researchers identified two groups of genes that could discriminate among the three groups of mice.

"Our results show that this new gene-signature test works well to find candidemia in mice that had the infection versus mice without infection," said co-lead author Aimee Zaas, assistant professor of medicine in the Duke division of infectious diseases and international health.

"We were very pleased to learn that we could further distinguish the fungal infection from a staph infection, another bloodstream disease that shares the same set of symptoms," she added.

Moreover, the researchers identified distinct groups of genes that correlate with blood samples at different points during the course of the infection. With this data, Zaas and her colleagues believe that doctors may be able to differentiate between early and late stages of the infection, and can modify treatment options accordingly.

Although the study was conducted using an animal model, the researchers are now working on a gene-expression test that can differentiate candidemia from other infectious diseases in humans.

"This work is part of a portfolio of blood gene-expression-based tests we are developing to detect viral, bacterial and now fungal infections that will lead to more precise diagnosis and more appropriate therapies for infectious disease," said co-author Geoffrey Ginsburg, director of the university's Center for Genomic Medicine. "This is personalized medicine."

The findings appear in the current issue of the journal Science Translational Medicine.